In Vivo Dynamic Lumbar Vertebral Motion and Disc Deformation During Lifting Tasks

描述（由申请人提供）：在美国，腰背部疾病（lbd）仍然是最普遍、最令人衰弱、最昂贵的职业健康问题之一。腰椎的机械负荷是导致和预防职业性腰痛的主要因素。评估腰骶（L5-S1）椎间盘机械力的现有知识和方法基础主要来自静态和/或体外尸体研究，或来自体内动态研究，这些研究不能确定内部椎体运动或椎间盘变形。它们在评估与动态工作活动（如手动举重）相关的腰背部疾病或伤害风险方面的适用性有限。我们的首要假设是，更准确地了解负重过程中腰椎的动态反应将有助于更有效地预防和控制腰痛。这项探索性研究的目的是描述腰椎的动态响应与由负载和举重运动学（即动态姿势）定义的举重动力学之间的关系，并开始开发一个改进的模型来评估与手工任务相关的腰背部机械应力。该研究将利用最先进的动态放射照相系统，该系统能够以前所未有的精度测量体内腰椎的运动学，以及我们在研究负重举重的生物力学方面的丰富经验。我们将追求两个具体目标：目标1是表征腰椎运动学和动态抬起姿势之间的关系以及抬起的负荷对这种关系的影响；我们将使用动态x射线系统获取腰椎的运动学数据，并使用运动捕捉系统在执行举重任务期间获取全身举重运动学数据。目的2表征L5-S1椎间盘变形与压缩力分布的动态关系；我们将创建一个新的“弹簧加载摆动平台”模型来表征这种关系，并使用Aim 1中获得的数据进行经验指定；我们将比较基于新的动态关系和不考虑动态椎间盘变形的传统方法确定的L5-S1椎间盘压缩力。提出的项目是第一次尝试调查真正的动态和活体力学行为的腰椎在举重活动。它将为开发更先进的能力铺平道路，以评估或预测动态手动提升过程中的下背部机械应力。它也将提供一个独特的机会来建立新的标准（例如，基于体内应变而不是基于应力）的椎间盘组织耐受/失败。这项工作，以及随后的一系列系统研究，将产生新的知识体系和下一代指南、模型和工具，以更好地识别、评估和控制职业性腰背部疾病的风险。

DESCRIPTION (provided by applicant): Low back disorders (LBDs) remain one of most prevalent, debilitating, and costly occupational health problems in the United States. Mechanical loading on the lumbar spine is a central factor in the causation and prevention of occupational LBDs. The existing knowledge and methodological bases for evaluating mechanical forces on the lumbo-sacral (L5-S1) inter-vertebral disc were largely developed from static and/or in vitro cadaveric studies, or from in vivo dynamic studies that did not determine the internal vertebral movement or disc deformation. They are limited in their applicability in assessing the low back disorder or injury risks associated with dynamic work activities such as manual load lifting. Our overarching hypothesis is that more accurate understanding of the dynamic responses of lumbar spine during load-lifting will lead to more effective prevention and control of LBDs. The objective of this exploratory study is to characterize the relationships between dynamic responses of the lumbar spine and lifting dynamics defined by the load and lifting kinematics (i.e., dynamic postures), and begin to develop an improved model for evaluating the low back mechanical stress associated with manual tasks. The study will take advantage of a state-of-the-art dynamic radiographic system capable of measuring lumbar vertebral kinematics in vivo with unprecedented accuracy, and our extensive experience of studying the biomechanics of load lifting. We will pursue two specific aims: Aim 1 is to characterize the relationship between lumbar vertebral kinematics and dynamic lifting posture and the effect of load lifted on the relationship; we will acquire data of the lumbar vertebral kinematics using the dynamic X-ray system and the whole-body lifting kinematics using a motion capture system during the performance of lifting tasks. Aim 2 is to characterize the dynamic relationship between L5-S1 disc deformation and compressive force distribution; we will create a novel "spring-loaded wobbling platform" model to characterize this relationship and specify it empirically using data obtained from Aim 1; we will compare the L5-S1 disc compressive forces determined based on the new dynamic relationship and by the conventional approach which does not take into account the dynamic disc deformation. The proposed project is the first attempt to investigate the truly dynamic and in vivo mechanical behavior of the lumbar spine during lifting activities. It will pave the way for developing much improved capabilities to assess or predict low back mechanical stress during dynamic manual lifting. It will also afford a unique opportunity to establish new criteria (e.g., in vivo strain-based instead of stress-based) for disc tissue tolerance/failure. This work, along with a series of systematic studies that would naturally follow, will lead to a new body of knowledge and next-generation guidelines, models, and tools for better recognition, evaluation, and control of the risk of occupational low back disorders. PUBLIC HEALTH RELEVANCE: Mechanical loading on the lumbar spine is a central factor in causing and preventing low back disorders (LBDs) which are one of the leading occupational health problems. The existing knowledge and tools for evaluating the spinal loading are based on studies having only limited relevance and applicability to real work activities such as load lifting. The proposed research will develop new scientific knowledge and tools for more accurate assessment of the risk of LBDs associated with load lifting tasks.